A dental floss product is generally advised as a means for treating inter-proximal and sub-gingival areas in the oral cavity to supplement brushing of teeth. Flossing comprises manoeuvring the floss product between teeth, and gently moving up and down against the surface of the teeth to remove inter-dental plaque and debris, including sub-gingival plaque. Plaque is constantly being formed on tooth surfaces, and if not regularly removed plaque can cause tooth cavities and gum disease. During flossing, the floss product should loosen or break up plaque from the surface and transport it away from the teeth. A dental floss product should thus have dimensions that allow insertion and rubbing between teeth, yet be strong enough to withstand the forces accompanied therewith.
The most commonly used dental floss comprises a plurality of filaments, made from polymers like polyamides or polyolefins. Such multi-filament floss is usually waxed to hold the filaments together, and to lubricate the floss. European application EP 0339935 A3 discloses a particular embodiment of a dental floss composed of a multifilament of ultrahigh-molecular weight polyethylene, having good mechanical properties. The dental floss was prepared by bundling a multiplicity of drawn oriented filaments to produce an multifilament having a tensile strength of 2.5 GPa, modulus of 90 GPA and an elongation to break of 4.1%.
An alternative form of dental floss is dental tape, also optionally waxed and flavoured. Both multi-filament and tape floss products are stated to have specific advantages and disadvantages; but selecting the optimum product also appears highly dependent on personal preferences of users.
Such a dental floss product comprising a unitary tape is known from EP 0662388 B1. In this patent specification a dental floss is described that comprises a unitary tape of about 0.03-0.13 mm thickness and of about 0.25-6.4 mm width, which tape is made from ultra-high molar mass polyethylene having a molar mass in the range of 300 to 6000 kg/mol, and which tape has a Young's modulus in the range of 0.5 to 10 GPa and a tensile strength of 0.1 to 1.2 GPa. It is indicated that this tape is not shredding into filaments during use, thereby making flossing more convenient and easier. Another indicated advantage of the product is that it is not coated with a waxy solid, because it is self-lubricating. The tape applied as floss was made by swelling a precursor tape of said polyethylene in paraffin oil into a pseudo-gel state, cooling the pseudo-gel under controlled conditions to ambient temperature, squeezing the swollen tape lightly to remove paraffin oil, treating the tape in hexane and heating the tape to around 70° C. to remove residual hexane to produce a porous tape having a greater porosity than said precursor tape, compressing the porous tape and then stretching the tape at 80-130° C. to obtain a drawn product.
A drawback of the known dental floss tape is that its mechanical properties are not sufficient in all circumstances, especially premature tearing and breakage of the tape may occur for example upon insertion between teeth that have very small inter-dental distance or that virtually contact each other at some point, or during flossing when contacting a sharp edge of for example a brace or bridge.
It is therefore an object of the present invention to provide a dental floss product comprising a unitary tape made from ultra-high molar mass polyethylene that does not, or at least to a reduced extent, show said disadvantage.
This object is achieved according to the invention with a dental floss product wherein the tape has a tensile strength of at least 1.8 GPa.
The dental floss product according to the invention has very high mechanical, especially tensile strength, shows high resistance to tearing and has a low coefficient of friction. The tape can be inserted between teeth tightly together without breaking. A further advantage of the dental tape according to the invention is that it retains most of its initial strength during flossing, even if the tape separates into filaments. Still another advantage is that hardly any pilling of the tape occurs, even upon fibrillation, meaning there is little risk of the tape getting stuck between teeth as a result of local thickening. The dental tape further has a high modulus and shows little elongation during use, allowing a precise and controlled flossing action.